As this type of device, for example, a waste-heat reusing device disclosed in Patent Document 1 has been known. The waste-heat reusing device disclosed in Patent Document 1 includes: a Rankine cycle equipped with a pump, a heater, an expander, and a condenser; a bypass flow passage which bypasses the expander; and a bypass valve that opens and closes the bypass flow passage. In addition, the pump, the expander, and a motor generator are connected to each other by a common drive shaft. Then, at the time of stopping the Rankine cycle, the waste-heat reusing device is configured to open the bypass valve and stop the motor generator by confirming that the differential pressure of the expander becomes sufficiently smaller, to thereby stop the pump and the expander.
In the waste-heat reusing device disclosed in Patent Document 1, the pump is driven by output of the expander and the motor generator is driven by excess output.